Instantaneous heater for liquids



Oct. 18, 1960 H. R. DAMMOND 2,957,059

rNsTANTANEoUs HEATER FOR LIQuIns Filed Nov. 2s. 195s INVENToR. HOWARD l?. DAMMOND United States y Patent C) INSTANTANEOUS HEATER FOR LIQUIDS Howard R. Dammond, New York, N.Y., assignor to Laudam Products Corporation, Great Neck, N.Y., a corporation of New York Filed Nov. 28, 1958, Ser. No. 776,821

Claims. (Cl. 219-39) This invention relates to heat exchangers and more particularly to electrically energized liquid heaters of the throughllow or instantaneous type adapted, for example, to be attached to a cold water faucet to furnish a continuous flow of heated water.

Electrically energized instantaneous water heaters dffer from the conventional boiler-water coil-immersion type of instantaneous water heater in that heat is not stored within the unit, but is generated only when hot water is being drawn. Lacking a stored supply of hot water for the running supply and lacking a heat reservoir in the form, for example, of a static supply of boiler water, electrically energized instantaneous heaters are relatively critical in their control. They can not tolerate heat energy when water is not being drawn, but they require heat energy at all times when water is being drawn.

It is, therefore, one object of the present invention to provide an improved electrically energized instantaneous liquid heater.

Another object of the invention is to provide an ins-tantaneous liquid heater adapted to be operated from a source of electrical current which is simple to manufacture and safe as well as eiicient in its operation.

In accordance with the present invention there is provided an instantaneous heating unit for liquids preferably taking the form of a small container or canister adapted to be attached to a cold water faucet and having an electrical cord adapted to be plugged into the mains to heat the water as it flows through the unit. Within the conrainer there is provided a pressure-sensing transducer responsive to the'pressure of the water to actuate a switch to establish an electrical circuit through a resistance heater. The back pressure is developed by providing concentric tubes having a common inlet, the inner tube of which passes through the transducer and is restricted in diameter to meter the llow. The outer tube is connected to the transducer chamber so that the back-pressure across the inner tube is reliected.

The resistance heater is fitted within a closed chamber in the container to be exposed to water passing therethrough. The heating chamber is so arranged through the use of spaced and offset inlet and outlet connections ice by the numeral 10, includes a casing 11 supporting an inlet tting 12 including a sealing flange 13 and a threaded coupler 14 adapted to be attached to a water faucet. The casing 11 which is preferably plastic and generally cylindrical in shape has extending from the base thereof an outlet fitting 15 including a perforated spray cap 16 frictionally secured on a depending stud 17 by an O-ring 18. The inner end of the stud 17, which is secured in a liquid tight seal as by brazing to the lower surface of a cupshaped metal member 21, constitutes a standpipe 19 projecting upwardly into a small water tight chamber 20 within the member 21. The cup-shaped member 21 has a relatively heavy cover 22 alxed thereto in a liquid tight seal. The member 21 is anchored to the casing 11 by the stud 17 which is threaded to receive a clamping nut 17a. A washer 19a seals Iagainst the entry of water into the casing 11.

The inlet fitting 12 is coupled to the chamber 20 by means of a narrow tube 23 which passes through the body of a pressure transducer 24 having a pressure chamber 25 bounded on one side by a llexible resilient diaphragm 26. The inside of the chamber 25 is also connected to the inlet fitting 12 by means of tube 27 concentric with respect to the tube 23 and defining a pressure-signal path to the transducer.

Mounted adjacent the diaphragm 26 is a single-pole single-throw momentary push switch 28 supported by the cover 22 of the closed chamber 20 by means of supporting lugs 29 and mounting screws 30 tapped therein. Supported by the housing of the switch 28 within the casing 11 is a thermal protector indicated generally by the numeral 31 which can take the form, for example, of a fusible link of electrically conducting material which melts in the presence of external temperature exceeding a predetermined value. The casing 11 is closed at its top by a cover portion 32 recessed within the casing. Secured to the cover portion 32 is a pilot light jewel 33. Also secured to the cover portion 22 is an electrical cord 34, the insulating covering of which is primed with a groove 34a to receive the cover. The space immediately labove the cover portion 32 is preferably lled with an electrically insulating sealing compound 35 such, for example, as epoxy resin, making the casing water tight.

that the Water is caused to pass closely about the resistance heater element. The entire unit is preferably grounded through the plumbing system so that it is free of electrical hazards and suitable thermal safeguards such as a thermal protector and a pilot'light are preferably inv eluded.

A preferred embodiment of the invention illustrating the above and other features and objects of the present invention is described below having reference to the accompanying drawing in which: Figure l is a View in vertical section of a faucet type instantaneous water heater taken on the staggered line 1-1 of Figure 2 looking in the direction of the arrows; and Figure 2 is a View in transverse section taken on the line 2-2 of Figure l, looking in the direction of the arrows.

Refem'ngto the drawing, the unit, identified generally Within the casing 11, the electrical conductors 36a and 36b of the electrical conduit 34 are connected respectively to the electrical switch 28 and to one terminal 37a of a resistance heater 37.

The resistance heater is supported by the cover 22 in the inner water-tight chamber 21 and its two terminal ends 37a and 37b extend through sealed openings 22a and 22b therein. The resistance heater is of the sheathed type, consisting of an inner element which is heated by the passage of electricity through it, and a sheath of copper or other suitable metal tubing. The inner heating element is suspended within the sheath in a suitable compacted substance such as powdered magnesium oxide, which serves to conduct the heat generated in the heating element to the sheath, and also to electrically insulate the heating element from the sheath. The terminal 37b of the heater 37 is connected to one terminal 31a of the thermal protector 31, the other terminal 31b of which is connected directly to the terminal 28a of the switch 28. Thus there is set up an electrical circuit including the conductor 36a of the electrical cord 34, the immersible resistance heating element 37, the thermal protector device 31, the single-pole single-throw push switch 28 and the conductor 36b of the cord 34. An indicator bulb 38 such, for example, as a neon bulb is disposed within the jewel 33 and is connected across the two terminals ot" the resistance heater element 37 through current hunting resistor 39 by conductor leads 40.

In operation with the coupling 12 attached in waterducer chamber 25 to flex the diaphragm 26 outwardly tov close the normally open contacts of theV push switch 2S. Electrical current then flows through Vthe resistance heater 37 to begin heating the relatively small supply of water within the inner chamber 20. Water flowing through the tube 23 will force water to be discharged Afrom the closed chamber 20 through the outletgstud 17V and the spray cap 16. After an extremely brief interval Athis water will flow hot due to the action of the heater 37 and will Vcontinue to flow hot so long as the supply is turnedon. This is due to the continuous flow of water downwardly onto the heater 37 and then generally horizontally V.along the heater to the top of the chamber 2'0 at the opposite end from the inlet and thence out of the dischargepfitting 15. The temperature of the water flowing outV of the unit is controlled by the valve of the cold water faucet. The lower the flow rate, the higher the temperature of the outow. If, however, the cold water flow is cut down to a value which would result in dangerously hot or pcssibly steaming water at the outlet, the back pressurehin the pressure chamberZS will fall by virtueof the decreased flow through the restricted tube 23, and Ythe switch 2S will open to de-energize the heater. 'Ihus a dripping faucet cannot `articulate the unit. Similarly, when the water supply is turned off, the'switcli will be open and the flow of electricity terminated.

While the invention has been described above having reference to a preferred embodiment thereof, it willl be understood that it can take various other forms and arrangements and should not, therefore, be regarded as limited except as defined in the following claims.

I claim: v

l. A heat exchanger unit for heatingl flowing liquid comprising a housing having an inlet fitting adapted yto be attached to a valved source offlowing liquid, a closed 'liquid-tight chamber in the housing having a liquid inlet land liquid outlet spaced therefrom, means including a 'restricted flow conduit to connect the liquid flow to the inlet of the chamber, an electrical resistance heater -in the rchamber interposed in the flow path between the inlet and outlet, a pressure transducer including a closed volume surrounding the restricted flow conduitY and connected to the liquid inlet end thereof, saidpressure transducer including a flexible diaphragm as one'wall thereof, a normally open momentary switch adjacent the diaphragm and Iadapted to be closed upon expansion of the diaphragm under the influence of liquid pressure in the transducer, and electrical conduit means connected to said resistance heater and including said momentary switch in series therewith, whereby a flow of liquid through the unit exceeding a predetermined minimum :actuates the transducer to energize the heater whereby the temperature of the liquid flowing through the unit is a direct function of the volume of the waterfflowing through the unit, said housing being generally cylindrical, said chamber being disposed in the lower portio-n of the housying and comprising a generally cylindrical configuration, .the diameter of which greatly exceeds the altitude, said heater element comprising a length of insulated resistance heater wire entering the chamber through the top and extending parallel to the upper and lower surfaces thereof, said inlet communicating With the chamber at a point spaced from the outlet and connected to discharge into the upper portion thereof, said outlet including ja standpipe extending up through the lower Vsurface of the chamber to a point adjacent the upper surface.

-2. Apparatus set ifoA claim l including a theyr- 4 Y mal protector element mounted above the chamber an connected in series with the electrical circuit, said thermal protector including a fusible link adapted to melt under the inlluence of heat generated in excessive quantity within said chamber.

3. A heat exchanger unit for heating flowing liquid comprising a housing having an inlet fitting adapted to be -attached to a valved source of flowing liquid, a closed liquid-tight chamber in the housing having a liquid inlet and liquid outlet spaced therefrom', means including a restricted flow conduit to connect the liquid flow to the inlet of the chamber, an electrical resistance heater in the chamber interposed in the flow path between the inlet and outlet, a pressure transducer including a closed volume surrounding the restricted flow conduit and connected to the liquid inlet end thereof, said pressure transducer including a flexible diaphragm as one wall thereof, a normally open momentary switch adjacent thejdiaphragm and adapted to be closed upon expansion of the diaphragm under the influence of liquidpressure inthe transducer, and electrical, conduit means connected to said resistance heater and including said momentary switch in series therewith, whereby a flow of` liquid through the unit exceeding a predetermined minimum actuates the transducer to energize the heater whereby thel temperature of the liquid flowing through the unit isa direct function of the volume of the water flowing through the unit, said outlet opening comprising a tubular memberV secured to the base of said housing and tothe base of the chamber and passing Vupwardly through the lowerl wall of the chamber to a point closely adjacent the upper surface thereof, said chamber thereby being securedto the container, a friction ring surrounding the tubular outlet member projecting beneath the container and a perforated spray vcap fitted over the depending end of the tubular member and the friction ring therein. e w

4. A heat exchanger unit for heatingV flowing liquid comprising a housing having an inlet fitting adapted to be attached to a valved source of flowing liquid, a closed liquid-tight chamber in the housing having a liquid inlet and liquid outlet spaced therefrom, means including.V a restricted flow conduit to connect the liquid flow to the inlet of the chamber, an electrical resistance heater `in the chamber interposed in the flow path between theY inlet and outlet, a pressure transducer including aclosedvol-l urne surrounding the restricted flow conduit and connected to the liquid inlet end thereof, said pressure transducer including a flexible diaphragm as one wall thereof, a normally open momentary switch adjacent the'diaphragm and adapted to be closedV upon expansionofthe diaphragm under the influenceof liquid pressure inthe transducer, and electrical Vconduit vmeans connected to said resistance heater and including said momentary switch in series therewith, wherebyV a v flow of liquid through the unit exceeding a predeterminedv minimum actuates the ytransducer to energize the heater whereby the temperature of the liquid flowing through the unit is na direct function of the volume of the'water flowing through the unit, said housing being generally cylindrical, a cover portion recessed in the upper portion of the container and a water-proof plastic layer surmounting said cover portion in sealing relationship with the container, said electrical conduit means being vsecured tothe cover portion and partially embedded in the plastic layer. e

5. A heat exchanger unit for heating flowing liquid comprising a housing having an inlet -fittingadapted to be attached to a valved source of flowing liquid, a closed liquid-tight chamber in the housing Vhaving a liquid inlet and liquid outlet spaced therefrom, means including a restricted flow conduit to `connect the liquid flow to the inlet of the chamber, an electrical resistance heaterrin the chamber interposed in the flow pathl between the/inlet and outlet, a pressure transducer 'including a closed volume surrounding the restricted wfconduit and; 'c'on- IVtQQted to the liquid 'inlet "end thereof, said pressure -transducer including a exible diaphragm as one wall thereof, a normally open momentary switch adjacent the diaphragm and adapted to be closed upon expansion of the diaphragm under the inuence of liquid pressure in the transducer, and electrical conduit means connected to said resistance heater and including said momentary switch in series therewith, whereby a flow of liquid through the unit exceeding a predetermined minimum actuates the transducer to energize the heater whereby the temperature of the liquid owing through the unit is a direct function of the volume of the water owing through the unit, including a liquid inlet fitting, said transducer comprising a generally tubular body portion, an inlet con- References Cited in the le of this patent UNITED STATES PATENTS 942,874 Stevens Dec. 7, 1909 1,057,760 Miles Apr. 1, 1913 1,462,703 Jones Iuly 24, 1923 FOREIGN PATENTS 626,804 Great Britain July 21, 1949 

